Abstract
It was found that GaAs was etched effectively by atomic hydrogen generated by a tungsten (W) filament. The experiment was performed in a pure H2 gas or H2 and He gas mixture at atmospheric pressure. The W-filament was heated up to 2000°C. The GaAs was etched with a smooth surface in pure H2 gas and the etching rate was as high as 15 µm/h at a substrate temperature of 850°C, though the etching rate was low and the surface was rough with Ga droplets in He gas. These results suggest that Ga is removed from the GaAs surface as a hydride such as GaH3.